Effect of Low-Energy Gallium-Aluminum-Arsenide and Aluminium Gallium Indium Phosphide Laser Irradiation on the Viability of C2C12 Myoblasts in a Muscle Injury Model

Objective: To evaluate the effect of phototherapy on the viability of cultured C2C12 myoblasts under different nutritional conditions (muscle injury model) using low-energy gallium-aluminum-arsenide (GaAlAs) and aluminium-gallium-indium-phosphide (InGaAlP) lasers with different wavelengths and powers. Background Data: The beneficial effects of phototherapy using low-energy lasers depend on irradiation parameters and type of laser used, but there are no data in the literature on C2C12 myoblasts proliferation after phototherapy with GaAlAs and InGaAlP lasers. Methods: A C2C12 cell line cultured in regular (10% fetal bovine serum, FBS) and nutrient-deficient (5% FBS) media were irradiated with low-energy GaAlAs (660 nm) and InGaAlP (780 nm) lasers with energy densities of 3.8, 6.3, and 10 J/cm(2), and 3.8, 10, and 17.5 J/cm(2), respectively. Cell proliferation was assessed indirectly 24 h after irradiation by measuring the mitochondrial activity and using the crystal violet assay. Results: There were no significant differences in cell viability between laser-treated myoblasts and control cultures for all tested parameters after 24 h of cell culture, although cell cultures grown in regular nutrient medium supplemented with 10% FBS exhibited higher growth rates than cultures, irradiated or not, grown in nutrient-deficient medium. Conclusion: Laser phototherapy did not improve C2C12 viability under regular or nutrient-deficient (muscle injury model) conditions using the above parameters.